2008 GMC Yukon Owner's Manual - Page 434

(E) Tire Ply Material: The type of cord and number of plies in the sidewall and under the tread. (F) Uniform Tire Quality Grading (UTQG): Tire manufacturers are required to grade tires based on three performance factors: treadwear, traction, and temperature resistance. For more information, see Uniform Tire Quality Grading on page 5-83. (G) Maximum Cold Inflation Load Limit: Maximum load that can be carried and the maximum pressure needed to support that load. For information on recommended tire pressure see Inflation - Tire Pressure on page 5-72 and Loading Your Vehicle on page 4-35. Light Truck (LT-Metric) Tire (A) Tire Size: The tire size code is a combination of letters and numbers used to define a particular tire's width, height, aspect ratio, construction type, and service description. See the "Tire Size" illustration later in this section for more detail. 5-66